Testing and Assessment - Reliability and Validity
Reliability and validity are important concepts not be any necessary relationship between the two. Be wary of statements which imply that a valid test or measure has to be reliable. Test-retest reliability is a measure of reliability obtained by administering the the split-half reliability is obtained by determining the correlation between the two . Reliability and validity are two concepts that are important for defining and exams should be reliable – it should not make any difference whether a student takes the Reliability is stated as correlation between scores of Test 1 and Test 2.
The scale is reliable because it consistently reports the same weight every day, but it is not valid because it adds 5lbs to your true weight. It is not a valid measure of your weight. Types of Validity 1. Face Validity ascertains that the measure appears to be assessing the intended construct under study. The stakeholders can easily assess face validity.
If the stakeholders do not believe the measure is an accurate assessment of the ability, they may become disengaged with the task. If a measure of art appreciation is created all of the items should be related to the different components and types of art.
If the questions are regarding historical time periods, with no reference to any artistic movement, stakeholders may not be motivated to give their best effort or invest in this measure because they do not believe it is a true assessment of art appreciation. Construct Validity is used to ensure that the measure is actually measure what it is intended to measure i. The experts can examine the items and decide what that specific item is intended to measure. Students can be involved in this process to obtain their feedback.
The questions are written with complicated wording and phrasing. It is important that the measure is actually assessing the intended construct, rather than an extraneous factor. Criterion-Related Validity is used to predict future or current performance - it correlates test results with another criterion of interest. You should be careful that any test you select is both reliable and valid for your situation.
A test's validity is established in reference to a specific purpose; the test may not be valid for different purposes. For example, the test you use to make valid predictions about someone's technical proficiency on the job may not be valid for predicting his or her leadership skills or absenteeism rate.
This leads to the next principle of assessment. Similarly, a test's validity is established in reference to specific groups. These groups are called the reference groups. The test may not be valid for different groups. For example, a test designed to predict the performance of managers in situations requiring problem solving may not allow you to make valid or meaningful predictions about the performance of clerical employees.
If, for example, the kind of problem-solving ability required for the two positions is different, or the reading level of the test is not suitable for clerical applicants, the test results may be valid for managers, but not for clerical employees. Test developers have the responsibility of describing the reference groups used to develop the test.
The manual should describe the groups for whom the test is valid, and the interpretation of scores for individuals belonging to each of these groups.
You must determine if the test can be used appropriately with the particular type of people you want to test. This group of people is called your target population or target group. Use assessment tools that are appropriate for the target population. Your target group and the reference group do not have to match on all factors; they must be sufficiently similar so that the test will yield meaningful scores for your group.
For example, a writing ability test developed for use with college seniors may be appropriate for measuring the writing ability of white-collar professionals or managers, even though these groups do not have identical characteristics. In determining the appropriateness of a test for your target groups, consider factors such as occupation, reading level, cultural differences, and language barriers. Recall that the Uniform Guidelines require assessment tools to have adequate supporting evidence for the conclusions you reach with them in the event adverse impact occurs.
A valid personnel tool is one that measures an important characteristic of the job you are interested in. Use of valid tools will, on average, enable you to make better employment-related decisions.
Relation between Validity and Reliability of a Test
Both from business-efficiency and legal viewpoints, it is essential to only use tests that are valid for your intended use. In order to be certain an employment test is useful and valid, evidence must be collected relating the test to a job. The process of establishing the job relatedness of a test is called validation. Methods for conducting validation studies The Uniform Guidelines discuss the following three methods of conducting validation studies. The Guidelines describe conditions under which each type of validation strategy is appropriate.
Difference Between Validity and Reliability (with Comparison Chart) - Key Differences
They do not express a preference for any one strategy to demonstrate the job-relatedness of a test. Criterion-related validation requires demonstration of a correlation or other statistical relationship between test performance and job performance. In other words, individuals who score high on the test tend to perform better on the job than those who score low on the test.
If the criterion is obtained at the same time the test is given, it is called concurrent validity; if the criterion is obtained at a later time, it is called predictive validity.
Content-related validation requires a demonstration that the content of the test represents important job-related behaviors. In other words, test items should be relevant to and measure directly important requirements and qualifications for the job. Construct-related validation requires a demonstration that the test measures the construct or characteristic it claims to measure, and that this characteristic is important to successful performance on the job.
The three methods of validity-criterion-related, content, and construct-should be used to provide validation support depending on the situation. These three general methods often overlap, and, depending on the situation, one or more may be appropriate.
- Chapter 3: Understanding Test Quality-Concepts of Reliability and Validity
- Difference Between Validity and Reliability
French offers situational examples of when each method of validity may be applied. First, as an example of criterion-related validity, take the position of millwright. Employees' scores predictors on a test designed to measure mechanical skill could be correlated with their performance in servicing machines criterion in the mill. If the correlation is high, it can be said that the test has a high degree of validation support, and its use as a selection tool would be appropriate. Second, the content validation method may be used when you want to determine if there is a relationship between behaviors measured by a test and behaviors involved in the job.
For example, a typing test would be high validation support for a secretarial position, assuming much typing is required each day. If, however, the job required only minimal typing, then the same test would have little content validity.
Reliability and validity
Content validity does not apply to tests measuring learning ability or general problem-solving skills French, Finally, the third method is construct validity. This method often pertains to tests that may measure abstract traits of an applicant.
For example, construct validity may be used when a bank desires to test its applicants for "numerical aptitude. To demonstrate that the test possesses construct validation support, ". Professionally developed tests should come with reports on validity evidence, including detailed explanations of how validation studies were conducted.
If you develop your own tests or procedures, you will need to conduct your own validation studies. On the other hand, validity is the correlation of the test with some outside external criteria. A test to be valid, has to be reliable.
Relation between Validity and Reliability of a Test
A test which possesses poor reliability is not expected to yield high validity. To be valid a test must be reliable. Tests with low reliability cannot be highly valid.
Validity may be said as correctness of measurement. If a test is heterogeneous, it has low reliability and high validity. On the other hand, maximum validity requires items differing in difficulty and low inter-correlation among items.
The validity of a test may not be higher than the reliability index. Validity is the proportion of common factor variance.
A valid test is always reliable. If a test truthfully measures what it purports to measure is both valid and reliable.